The invention pertains to electrical devices which contain monitoring circuitry wherein such circuitry emits audible warning signals that a parameter which has been monitored is exhibiting a trouble indicator. More particularly, the invention pertains to ambient condition detectors which contain internal monitoring circuitry and which also contain circuits for silencing an audible indicator which is indicating that a monitored condition needs attention or service.
Smoke detectors which contain alarm silencing circuitry are known. Such circuitry makes it possible to temporarily silence a detector which has gone into alarm due to a non-hazardous condition. Such conditions include stray smoke due to cigarettes, cigars or cooking. In known detectors, a user in the immediate area can depress a button or switch on the detector and temporarily silence an audible alarm in the presence of such nuisance conditions.
As an alternate to manually actuating a switch on a detector, systems are known for remotely suppressing nuisance alarms temporarily. One such system and method is disclosed in Bellavia et al U.S. Pat. No. 4,901,056.
Nuisance alarm conditions usually are initiated by exterior ambient conditions which are being sensed. Known detectors also monitor internal conditions which include, for battery powered detectors, battery energy levels. Where the monitored condition exhibits an out of range condition, such as a low battery, low battery audio and visible indicators can be energized.
Despite their informational value, such audible indicators can also be a nuisance. This is particularly the case where an out of range condition occurs at night when the people in the immediate area may not be able to alleviate the condition.
There continues to be a need for electrical units which monitor internal operational conditions where alarms associated therewith can be temporarily silenced. It would be especially desirable in such silencing circuitry did not appreciably add to cost or manufacturing complexity.
An ambient condition detector includes a housing and at least one ambient condition sensor carried by the housing. Control circuitry, which could include a programmed processor, is coupled to the sensor and includes circuits and/or executable instructions to determine if an alarm has been sensed.
The control circuitry also includes monitoring circuitry. The monitoring circuitry monitors one or more internal conditions apart from the one or more ambient conditions that are normally monitored. Examples include monitoring power supply or battery performance or output, and monitoring sensor performance to determine if the sensor, or sensors, exhibit acceptable clear air outputs. Other conditions can also be monitored.
In one aspect, for example, the detector includes manually activatable suppression circuitry which can be used to temporarily suppress a low power indicator produced by the monitoring circuitry provided that the element being monitored falls within one of at least three operational regions. Such indicators can be verbal or visible. The suppression circuitry can temporarily suppress either or both indicators. Other conditions can also be monitored and suppressed.
The sensor will continue to monitor the ambient while the condition indicator is suppressed. An alarm condition will be promptly reported even in the presence of a suppressed indicator.
The control circuitry can include an analog-to-digital converter for producing binary representations of condition indicating signals. The binary signals can be compared to a plurality of values in accordance with a pre-stored control program.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.